A set of specifications was developed for a Fourier transform ion cyclotron resonance mass spectrometer system (FT-ICR MS) fitted with external matrix-assisted laser desorption/ionization and electrospray ionization sources and cell(s) equipped for photodissociation. A series of test samples were prepared to test both the hardware and software. These were supplied to the three current manufacturers of FT-ICR MS systems (Bruker, Inc., Billerica, MA; Finnigan FTMS, Madison, WI; and IonSpec Corp., Irvine, CA) in order that they might generate representative data in the MS and MSn modes. Visits were made to each of these manufacturers and to a fourth company that was considering entry into the field and to a university site where an IonSpec instrument had just been installed. On the basis of these experiments, visits and subsequent discussions, the IonSpec system with a 7 Tesla actively shielded magnet was selected for the Resource. The purchase was initiated in December, 1997. Assembly and testing of the system are presently underway at the IonSpec, Corp. factory in Irvine, CA and the magnet is being manufactured in Oak Ridge, TN. Delivery in June 1998, is anticipated. The system will be equipped with turbomolecular pumps and the collision cells will have infrared transparent windows.. A carbon dioxide infrared laser (10.6 (m) will be purchased for use in the photodissociation experiments.